There is also the manner of the exit node of a tor connection, It's clear to any observers there. HAve a network of exit nodes and it's like the largest man-in-the-middle atteck ever.

It stands to reason. If you have ants or mice coming into your place and you know where, if you block it up, they'll get in another that you don't know about. But if you leave it open, you can see them come and go, see where they nest or what draws them. Of course redirect them and poison them more effectively.